Home > Exotic matter

Although no known particles have negative mass, physicists (primarily Robert L. Forward) have been able to describe some of the anticipated properties such particles may have. Negative mass would produce "negative gravity" that repels ordinary positive mass, but would be attracted to positive mass and other negative mass particles in a normal matter.

For a negative value of m₁ with positive value of m₂, F is negative (repulsive). At first glance it would appear that a negative mass would accelerate away from a positive mass, but by Newton's law

If m is negative and F is negative, then a must be positive - the negative mass accelerates toward the positive mass. If m is positive, however, and F is still negative, then a is negative and the positive mass accelerates away from the negative mass. It can be shown that if m₁ and m₂ are of equal but opposite mass, then the combined system of positive and negative particles will accelerate indefinitely without any additional input into the system.

This behaviour is bizarre, in that it's completely inconsistent with our 'normal universe' common sense expected behaviour from working with positive masses, but it is completely mathematically consistent and introduces no apparent contradictions when physics analysis is performed on the behaviours.

Naïve first impressions are that this violates conservation of momentum and/or energy, but in fact if the masses are equal in magnitude, one being of positive value and the other negative, then the momentum of the system is zero if they both travel together and accelerate together, no matter what speed:

...and an equivalent equation can be calculated for K_e:

Forward also showed that if m(-) and m(+) are not the same magnitude of mass, the equations are still consistent.

Some of the behaviours this seems to introduce are really bizarre, such as a comingled positive matter gas and negative matter gas having the positive matter portion increase in temperature without bound. However, the negative matter portion gains negative temperature at the same rate, again balancing out.

Forward has proposed a design for spacecraft propulsion using negative mass that requires no energy input and no reaction mass to achieve arbitrarily high acceleration, though of course a major obstacle to the construction of such a spacecraft is the fact that negative mass remains purely hypothetical. See diametric drive.

The term Exotic matter is also casually attached to any material which would be difficult to produce (such as metallic hydrogen or a Bose-Einstein condensate) or which exhibits unusual properties (such as fullerenes or nanotubes), even though these materials are relatively mundane in their composition. It could also refer to material composed of some form of exotic atomAn exotic atom is an atom, which is to say a system of particles held together primarily by the force due to electric charge, containing one or more unusual constituents. Electrons may be replaced by other negative particles, e. a muon or a pi-minus, or t.

Compare to strange matterStrange matter (also known as quark matter is an ultra-dense phase of matter that is theorized to form inside particularly massive neutron stars. It is theorized that when the neutronium which makes up a neutron star is put under sufficient pressure due t, dark matterDark matter is matter that can't be detected by its emitted radiation but whose presence can be inferred from gravitational effects on visible matter such as stars and galaxies. Estimates of the amount of matter in the universe based on gravitational effe, WIMPThis article is about the hypothetical class of particles. In human-computer interaction, WIMP stands for the "window, icon, menu, pointer" paradigm. A wimp is also a person who lacks confidence, is irresolute and wishy-washy. The slang term is rumored to.